#include "StdAfx.h"
#include "G721Codec.h"


static short qtab_721[7] = {-124, 80, 178, 246, 300, 349, 400};
/*
* Maps G.721 code word to reconstructed scale factor normalized log
* magnitude values.
*/
static short	_dqlntab[16] = {-2048, 4, 135, 213, 273, 323, 373, 425,
425, 373, 323, 273, 213, 135, 4, -2048};

/* Maps G.721 code word to log of scale factor multiplier. */
static short	_witab[16] = {-12, 18, 41, 64, 112, 198, 355, 1122,
1122, 355, 198, 112, 64, 41, 18, -12};
/*
* Maps G.721 code words to a set of values whose long and short
* term averages are computed and then compared to give an indication
* how stationary (steady state) the signal is.
*/
static short	_fitab[16] = {0, 0, 0, 0x200, 0x200, 0x200, 0x600, 0xE00,
0xE00, 0x600, 0x200, 0x200, 0x200, 0, 0, 0};



#define abs(v) (v < 0 ? -v : v)
/*
* quan()
*
* quantizes the input val against the table of size short integers.
* It returns i if table[i - 1] <= val < table[i].
*
* Using linear search for simple coding.
*/

static int
quan(
	 int		val,
	 short		*table,
	 int		size)
{
	int		i;

	for (i = 0; i < size; i++)
		if (val < *table++)
			break;
	return (i);
}


__declspec( naked ) short _stdcall quanf( int		val)
{
	_asm
	{
		mov edx , [esp + 4]
		shl edx , 16
			or edx , 0x8000
			bsr eax , edx
			sub eax , 15
			ret 4
	}
}



/*
* fmult()
*
* returns the integer product of the 14-bit integer "an" and
* "floating point" representation (4-bit exponent, 6-bit mantessa) "srn".
*/
static int
fmult(
	  int		an,
	  int		srn)
{
	short		anmag, anexp, anmant;
	short		wanexp, wanmant;
	short		retval;

	anmag = (an > 0) ? an : ((-an) & 0x1FFF);
	anexp = quanf(anmag) - 6;
	anmant = (anmag == 0) ? 32 :
		(anexp >= 0) ? anmag >> anexp : anmag << -anexp;
	wanexp = anexp + ((srn >> 6) & 0xF) - 13;

	wanmant = (anmant * (srn & 077) + 0x30) >> 4;
	retval = (wanexp >= 0) ? ((wanmant << wanexp) & 0x7FFF) :	(wanmant >> -wanexp);

	return (((an ^ srn) < 0) ? -retval : retval);
}

/*
* g72x_init_state()
*
* This routine initializes and/or resets the g72x_state structure
* pointed to by 'state_ptr'.
* All the initial state values are specified in the CCITT G.721 document.
*/
static void g72x_init_state(
struct g72x_state *state_ptr)
{
	int		cnta;

	state_ptr->yl = 34816;
	state_ptr->yu = 544;
	state_ptr->dms = 0;
	state_ptr->dml = 0;
	state_ptr->ap = 0;
	for (cnta = 0; cnta < 2; cnta++) {
		state_ptr->a[cnta] = 0;
		state_ptr->pk[cnta] = 0;
		state_ptr->sr[cnta] = 32;
	}
	for (cnta = 0; cnta < 6; cnta++) {
		state_ptr->b[cnta] = 0;
		state_ptr->dq[cnta] = 32;
	}
	state_ptr->td = 0;
}

/*
* predictor_zero()
*
* computes the estimated signal from 6-zero predictor.
*
*/
static short predictor_zero(
struct g72x_state *state_ptr)
{
	int		i;
	int		sezi;

	sezi = fmult(state_ptr->b[0] >> 2, state_ptr->dq[0]);
	for (i = 1; i < 6; i++)			/* ACCUM */
		sezi += fmult(state_ptr->b[i] >> 2, state_ptr->dq[i]);
	return short(sezi);
}
/*
* predictor_pole()
*
* computes the estimated signal from 2-pole predictor.
*
*/
static short predictor_pole(
struct g72x_state *state_ptr)
{
	return (fmult(state_ptr->a[1] >> 2, state_ptr->sr[1]) +
		fmult(state_ptr->a[0] >> 2, state_ptr->sr[0]));
}
/*
* step_size()
*
* computes the quantization step size of the adaptive quantizer.
*
*/
static short step_size(
struct g72x_state *state_ptr)
{
	int		y;
	int		dif;
	int		al;

	if (state_ptr->ap >= 256)
		return (state_ptr->yu);
	else {
		y = state_ptr->yl >> 6;
		dif = state_ptr->yu - y;
		al = state_ptr->ap >> 2;
		if (dif > 0)
			y += (dif * al) >> 6;
		else if (dif < 0)
			y += (dif * al + 0x3F) >> 6;
		return short(y);
	}
}

/*
* quantize()
*
* Given a raw sample, 'd', of the difference signal and a
* quantization step size scale factor, 'y', this routine returns the
* ADPCM codeword to which that sample gets quantized.  The step
* size scale factor division operation is done in the log base 2 domain
* as a subtraction.
*/
static short quantize(
					  int		d,	/* Raw difference signal sample */
					  int		y,	/* Step size multiplier */
					  short		*table,	/* quantization table */
					  int		size)	/* table size of short integers */
{
	short		dqm;	/* Magnitude of 'd' */
	short		exp;	/* Integer part of base 2 log of 'd' */
	short		mant;	/* Fractional part of base 2 log */
	short		dl;	/* Log of magnitude of 'd' */
	short		dln;	/* Step size scale factor normalized log */
	int		i;

	/*
	* LOG
	*
	* Compute base 2 log of 'd', and store in 'dl'.
	*/
	dqm = abs(d);
	exp = quanf(dqm >> 1);
	mant = ((dqm << 7) >> exp) & 0x7F;	/* Fractional portion. */
	dl = (exp << 7) + mant;

	/*
	* SUBTB
	*
	* "Divide" by step size multiplier.
	*/
	dln = dl - (y >> 2);

	/*
	* QUAN
	*
	* Obtain codword i for 'd'.
	*/
	i = quan(dln, table, size);
	if (d < 0)			/* take 1's complement of i */
		return ((size << 1) + 1 - i);
	else if (i == 0)		/* take 1's complement of 0 */
		return ((size << 1) + 1); /* new in 1988 */
	else
		return (short)i;
}
/*
* reconstruct()
*
* Returns reconstructed difference signal 'dq' obtained from
* codeword 'i' and quantization step size scale factor 'y'.
* Multiplication is performed in log base 2 domain as addition.
*/
static short reconstruct(
						 int		sign,	/* 0 for non-negative value */
						 int		dqln,	/* G.72x codeword */
						 int		y)	/* Step size multiplier */
{
	short		dql;	/* Log of 'dq' magnitude */
	short		dex;	/* Integer part of log */
	short		dqt;
	short		dq;	/* Reconstructed difference signal sample */

	dql = dqln + (y >> 2);	/* ADDA */

	if (dql < 0) {
		return ((sign) ? -0x8000 : 0);
	} else {		/* ANTILOG */
		dex = (dql >> 7) & 15;
		dqt = 128 + (dql & 127);
		dq = (dqt << 7) >> (14 - dex);
		return ((sign) ? (dq - 0x8000) : dq);
	}
}


/*
* update()
*
* updates the state variables for each output code
*/
static void update(
				   int		code_size,	/* distinguish 723_40 with others */
				   int		y,		/* quantizer step size */
				   int		wi,		/* scale factor multiplier */
				   int		fi,		/* for long/short term energies */
				   int		dq,		/* quantized prediction difference */
				   int		sr,		/* reconstructed signal */
				   int		dqsez,		/* difference from 2-pole predictor */
struct g72x_state *state_ptr)	/* coder state pointer */
{
	int		cnt;
	short		mag, exp;	/* Adaptive predictor, FLOAT A */
	short		a2p;		/* LIMC */
	short		a1ul;		/* UPA1 */
	short		pks1;	/* UPA2 */
	short		fa1;
	char		tr;		/* tone/transition detector */
	short		ylint, thr2, dqthr;
	short  		ylfrac, thr1;
	short		pk0;

	pk0 = (dqsez < 0) ? 1 : 0;	/* needed in updating predictor poles */

	mag = dq & 0x7FFF;		/* prediction difference magnitude */
	/* TRANS */
	ylint = state_ptr->yl >> 15;	/* exponent part of yl */
	ylfrac = (state_ptr->yl >> 10) & 0x1F;	/* fractional part of yl */
	thr1 = (32 + ylfrac) << ylint;		/* threshold */
	thr2 = (ylint > 9) ? 31 << 10 : thr1;	/* limit thr2 to 31 << 10 */
	dqthr = (thr2 + (thr2 >> 1)) >> 1;	/* dqthr = 0.75 * thr2 */
	if (state_ptr->td == 0)		/* signal supposed voice */
		tr = 0;
	else if (mag <= dqthr)		/* supposed data, but small mag */
		tr = 0;			/* treated as voice */
	else				/* signal is data (modem) */
		tr = 1;

	/*
	* Quantizer scale factor adaptation.
	*/

	/* FUNCTW & FILTD & DELAY */
	/* update non-steady state step size multiplier */
	state_ptr->yu = y + ((wi - y) >> 5);

	/* LIMB */
	if (state_ptr->yu < 544)	/* 544 <= yu <= 5120 */
		state_ptr->yu = 544;
	else if (state_ptr->yu > 5120)
		state_ptr->yu = 5120;

	/* FILTE & DELAY */
	/* update steady state step size multiplier */
	state_ptr->yl += state_ptr->yu + ((-state_ptr->yl) >> 6);

	/*
	* Adaptive predictor coefficients.
	*/
	if (tr == 1) {			/* reset a's and b's for modem signal */
		state_ptr->a[0] = 0;
		state_ptr->a[1] = 0;
		state_ptr->b[0] = 0;
		state_ptr->b[1] = 0;
		state_ptr->b[2] = 0;
		state_ptr->b[3] = 0;
		state_ptr->b[4] = 0;
		state_ptr->b[5] = 0;
	} else {			/* update a's and b's */
		pks1 = pk0 ^ state_ptr->pk[0];		/* UPA2 */

		/* update predictor pole a[1] */
		a2p = state_ptr->a[1] - (state_ptr->a[1] >> 7);
		if (dqsez != 0) {
			fa1 = (pks1) ? state_ptr->a[0] : -state_ptr->a[0];
			if (fa1 < -8191)	/* a2p = function of fa1 */
				a2p -= 0x100;
			else if (fa1 > 8191)
				a2p += 0xFF;
			else
				a2p += fa1 >> 5;

			if (pk0 ^ state_ptr->pk[1])
				/* LIMC */
				if (a2p <= -12160)
					a2p = -12288;
				else if (a2p >= 12416)
					a2p = 12288;
				else
					a2p -= 0x80;
			else if (a2p <= -12416)
				a2p = -12288;
			else if (a2p >= 12160)
				a2p = 12288;
			else
				a2p += 0x80;
		}

		/* TRIGB & DELAY */
		state_ptr->a[1] = a2p;

		/* UPA1 */
		/* update predictor pole a[0] */
		state_ptr->a[0] -= state_ptr->a[0] >> 8;
		if (dqsez != 0)
			if (pks1 == 0)
				state_ptr->a[0] += 192;
			else
				state_ptr->a[0] -= 192;

		/* LIMD */
		a1ul = 15360 - a2p;
		if (state_ptr->a[0] < -a1ul)
			state_ptr->a[0] = -a1ul;
		else if (state_ptr->a[0] > a1ul)
			state_ptr->a[0] = a1ul;

		/* UPB : update predictor zeros b[6] */
		for (cnt = 0; cnt < 6; cnt++) {
			if (code_size == 5)		/* for 40Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 9;
			else			/* for G.721 and 24Kbps G.723 */
				state_ptr->b[cnt] -= state_ptr->b[cnt] >> 8;
			if (dq & 0x7FFF) {			/* XOR */
				if ((dq ^ state_ptr->dq[cnt]) >= 0)
					state_ptr->b[cnt] += 128;
				else
					state_ptr->b[cnt] -= 128;
			}
		}
	}

	for (cnt = 5; cnt > 0; cnt--)
		state_ptr->dq[cnt] = state_ptr->dq[cnt-1];
	/* FLOAT A : convert dq[0] to 4-bit exp, 6-bit mantissa f.p. */
	if (mag == 0) {
		state_ptr->dq[0] = (dq >= 0) ? 0x20 : 0xFC20;
	} else {
		exp = quanf(mag);
		state_ptr->dq[0] = (dq >= 0) ?
			(exp << 6) + ((mag << 6) >> exp) :
		(exp << 6) + ((mag << 6) >> exp) - 0x400;
	}

	state_ptr->sr[1] = state_ptr->sr[0];
	/* FLOAT B : convert sr to 4-bit exp., 6-bit mantissa f.p. */
	if (sr == 0) {
		state_ptr->sr[0] = 0x20;
	} else if (sr > 0) {
		exp = quanf(sr);
		state_ptr->sr[0] = (exp << 6) + ((sr << 6) >> exp);
	} else if (sr > -32768) {
		mag = -sr;
		exp = quanf(mag);
		state_ptr->sr[0] =  (exp << 6) + ((mag << 6) >> exp) - 0x400;
	} else
		state_ptr->sr[0] = (short)0xFC20;

	/* DELAY A */
	state_ptr->pk[1] = state_ptr->pk[0];
	state_ptr->pk[0] = pk0;

	/* TONE */
	if (tr == 1)		/* this sample has been treated as data */
		state_ptr->td = 0;	/* next one will be treated as voice */
	else if (a2p < -11776)	/* small sample-to-sample correlation */
		state_ptr->td = 1;	/* signal may be data */
	else				/* signal is voice */
		state_ptr->td = 0;

	/*
	* Adaptation speed control.
	*/
	state_ptr->dms += (fi - state_ptr->dms) >> 5;		/* FILTA */
	state_ptr->dml += (((fi << 2) - state_ptr->dml) >> 7);	/* FILTB */

	if (tr == 1)
		state_ptr->ap = 256;
	else if (y < 1536)					/* SUBTC */
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (state_ptr->td == 1)
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else if (abs((state_ptr->dms << 2) - state_ptr->dml) >=
		(state_ptr->dml >> 3))
		state_ptr->ap += (0x200 - state_ptr->ap) >> 4;
	else
		state_ptr->ap += (-state_ptr->ap) >> 4;
}



/*
* g721_encoder()
*
* Encodes the input vale of linear PCM, A-law or u-law data sl and returns
* the resulting code. -1 is returned for unknown input coding value.
*/
static int g721_encoder(struct g72x_state *state_ptr ,  int		sl)
{
	short		sezi, se, sez;		/* ACCUM */
	short		d;			/* SUBTA */
	short		sr;			/* ADDB */
	short		y;			/* MIX */
	short		dqsez;			/* ADDC */
	short		dq, i;

	sl >>= 2;			/* 14-bit dynamic range */

	sezi = predictor_zero(state_ptr);
	sez = sezi >> 1;
	se = (sezi + predictor_pole(state_ptr)) >> 1;	/* estimated signal */

	d = sl - se;				/* estimation difference */

	/* quantize the prediction difference */
	y = step_size(state_ptr);		/* quantizer step size */
	i = quantize(d, y, qtab_721, 7);	/* i = ADPCM code */

	dq = reconstruct(i & 8, _dqlntab[i], y);	/* quantized est diff */

	sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq;	/* reconst. signal */

	dqsez = sr + sez - se;			/* pole prediction diff. */

	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

	return (i);
}

/*
* g721_decoder()
*
* Description:
*
* Decodes a 4-bit code of G.721 encoded data of i and
* returns the resulting linear PCM, A-law or u-law value.
* return -1 for unknown out_coding value.
*/
static int g721_decoder(struct g72x_state *state_ptr , int		i)
{
	short		sezi, sei, sez, se;	/* ACCUM */
	short		y;			/* MIX */
	short		sr;			/* ADDB */
	short		dq;
	short		dqsez;

	i &= 0x0f;			/* mask to get proper bits */
	sezi = predictor_zero(state_ptr);
	sez = sezi >> 1;
	sei = sezi + predictor_pole(state_ptr);
	se = sei >> 1;			/* se = estimated signal */

	y = step_size(state_ptr);	/* dynamic quantizer step size */

	dq = reconstruct(i & 0x08, _dqlntab[i], y); /* quantized diff. */

	sr = (dq < 0) ? (se - (dq & 0x3FFF)) : se + dq;	/* reconst. signal */

	dqsez = sr - se + sez;			/* pole prediction diff. */

	update(4, y, _witab[i] << 5, _fitab[i], dq, sr, dqsez, state_ptr);

	return (sr << 2);	/* sr was 14-bit dynamic range */
}



G721Codec::G721Codec(void)
{
	m_bInit   = false; 
	state_ptr = &m_xG72x;
}

G721Codec::~G721Codec(void)
{
}

int G721Codec::Initialzie()
{
	g72x_init_state(state_ptr);

	m_bInit = true;

	return 0;
}

void G721Codec::EncodeG721(unsigned char * dst , short * src , unsigned count)
{
	count >>= 1;
	for (unsigned i = 0 ; i < count ; i++)
	{
		unsigned code0 = g721_encoder(state_ptr , src[i * 2 + 0]);
		unsigned code1 = g721_encoder(state_ptr , src[i * 2 + 1]);
		unsigned code = code0 + (code1 << 4);
		dst[i] = (unsigned char)code;
	}
}

void G721Codec::DecodeG721(short * dst , unsigned char * src , unsigned count)
{
	count >>= 1;
	for (unsigned i = 0 ; i < count ; i++)
	{
		unsigned code = src[i];
		int val0 = g721_decoder(state_ptr , code & 0xf);
		int val1 = g721_decoder(state_ptr , code >> 4);
		dst[i * 2 + 0] = (short)val0;
		dst[i * 2 + 1] = (short)val1;
	}
}